Final answer:
The Disbursing Officer should transfer the safekeeping deposit to the new command when a member is transferred, ensuring the funds' security and availability.
Step-by-step explanation:
If a member has been transferred to another command without withdrawing their safekeeping deposit, the action that the Disbursing Officer must take is to transfer the deposit to the new command. This ensures that the funds remain secure and are available to the member at their new location. It is not appropriate to immediately refund the deposit, hold it until the member requests it, or to forfeit the deposit, as these actions do not facilitate the continuous safekeeping of the member's funds.